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ALASKA VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Friday, October 11, 2013, 2:05 PM AKDT (Friday, October 11, 2013, 22:05 UTC)
56°11'52" N 159°23'35" W,
Summit Elevation 8225 ft (2507 m)
Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE
The latest phase of the 2013 eruption of Veniaminof resumed on October 6, 2013 after a month-long pause in activity. Similar to activity observed during the summer of 2013, the eruption is characterized by lava effusion and fountaining and production of intermittent small steam, gas, and ash plumes that rise hundreds of feet above the active vent. These plumes are typically restricted to within a few miles of the caldera, however a trace of ash fall was reported today from residents of Chignik Lake and Chignik Lagoon located 25-35 miles (40-55 km) to the east of the active vent, respectively. Seismic tremor associated with this activity has been gradually declining in amplitude over the past week, but numerous air waves associated with small explosions have been detected. These small explosions are similar to those observed during activity this past summer, when small ash plumes were generated. Elevated surface temperatures, consistent with lava effusion, have been detected over the past week in satellite images.
Ash fall from current activity is not expected to be significant and likely will be less than 1/16 inch, although areas within a few miles of the active cone could receive thicker amounts of ash fall. Information about volcanic ash and its potential effects can be found on the AVO web page (www.avo.alaska.edu). Lava flows that encounter ice in the summit caldera will generate small volumes of melt-water, but we do not anticipate any significant flooding associated with this eruption unless conditions at the volcano change significantly.
Throughout the current eruption, which began in June 2013, the volcano has experienced fluctuating levels of lava effusion and ash emission. Eruptive activity could intensify at any time, leading to higher and more far traveled ash plumes.
Mount Veniaminof volcano is an andesitic stratovolcano with an ice-filled 10-km diameter summit caldera located on the Alaska Peninsula, 775 km (480 mi) southwest of Anchorage and 35 km (22 mi) north of Perryville. Veniaminof is one of the largest (~ 300 km3) and most active volcanic centers in the Aleutian Arc and has erupted at least 13 times in the past 200 years. Recent significant eruptions of the volcano occurred in 1993-95 and 2005. Both were moderate Strombolian eruptions producing intermittent low-level jets of incandescent lava fragments, and low-level emissions of steam and ash from the main intracaldera cone. During the 1993-95 activity, a small lava flow was extruded into the summit caldera ice field producing an ice pit. Minor ash-producing explosions occurred in 2002, 2004, early 2005, November 2006, and February 2008. Previous historical eruptions have produced ash plumes that reached 6,000 m (20,000 ft) above sea level and ash fallout that blanketed areas within about 40 km (25 mi) of the volcano.
52°49'20" N 169°56'42" W,
Summit Elevation 5676 ft (1730 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW
Low-level unrest continues at Cleveland. Over the past week, several small explosions were detected by distant infrasound (pressure) sensor networks. Satellite images showed no volcanic ash emissions or any other evidence of eruptive activity.
Cleveland volcano forms the western half of Chuginadak Island, a remote and uninhabited island in the east central Aleutians. It is located about 75 km (45 mi.) west of the community of Nikolski, and 1500 km (940 mi.) southwest of Anchorage. The volcano's most recent significant eruption began in February, 2001 and it produced 3 explosive events that produced ash clouds as high as 12 km (39,000 ft) above sea level. The 2001 eruption also produced a rubbly lava flow and hot avalanche that reached the sea. The most recent minor ash emissions were observed in November 2012.
OTHER ALASKA VOLCANOES
Seismic activity is monitored in real time at 29 volcanoes in Alaska. Satellite images of all Alaskan volcanoes are analyzed daily for evidence of ash plumes and elevated surface temperatures. Some volcanoes may currently display anomalous behavior but are not considered to be at a dangerous level of unrest. Akutan, Aniakchak, Augustine, Dutton, Fisher, Fourpeaked, Gareloi, Great Sitkin, Griggs, Iliamna, Isanotski, Kanaga, Katmai, Mageik, Makushin, Martin, Novarupta, Okmok, Pavlof, Redoubt, Shishaldin, Snowy, Spurr, Tanaga, Trident, Ugashik-Peulik, Ukinrek Maars, and Westdahl volcanoes are in color code GREEN
and volcano alert level Normal. All are at or near normal levels of background seismicity. AVO did not detect ash plumes or significant elevated surface temperatures in the vicinity of any of these volcanoes.
Please see http://www.avo.alaska.edu/color_codes.php
for complete definitions of Aviation color codes and Volcano alert levels.
VOLCANO INFORMATION ON THE INTERNET: http://www.avo.alaska.edu
RECORDING ON THE STATUS OF ALASKA'S VOLCANOES (907) 786-7478
John Power, Scientist-in-Charge, USGS
firstname.lastname@example.org (907) 786-7497
Jeff Freymueller, Coordinating Scientist, UAFGI
email@example.com (907) 378-7556
The Alaska Volcano Observatory is a cooperative program of the U.S. Geological Survey, the University of Alaska Fairbanks Geophysical Institute, and the Alaska Division of Geological and Geophysical Surveys.